Abstract

We report a way of tuning the flux pinning properties by controlling the size and number density of (BZO) nanorods without much degradation of the superconducting properties. The BZO nanorods in superconductingfilms are known as promising -axis-correlated pinning centers. We fabricated (SmBCO) films with BZO nanorods by a low-temperature growth technique (LTG-films). With decreasing substrate temperature of the upper layer in LTG-films, the diameter of BZO nanorods decreased and their number density increased, leading to a high matching field . Also, the considerable upturn shifts in the irreversibility field line and plateau regions in the magnetic field dependence of critical current density were observed in the range from to . These results indicate that a Bose-glass-like state of vortices localized on BZO nanorods emerges, after overcoming the vortex glass state of vortices, which are frozen on inherent pointlike disorders within the films in this magnetic field range. With this technique, it is possible to tune the flux pinning properties.

Received 09 June 2010Accepted 31 August 2010Published online 02 November 2010

Acknowledgments:

This work was supported in part by Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science, and Technology (Grant Nos. 19676005 and 20686065) and Grants-in-Aid for Scientific Research the Japan Society for the Promotion of Science (Grant No. 20-1311).